Add Progress Indicator

[peteamundson]

When running the anonymizer, it would be nice to see a progress indicator. Currently, when running this against a lot of data, the screen just displays that the operation is in progress instead of showing how long it has taken or how far along the process is.

[mskutta]

Can use XHR for this:

var xhr = new XMLHttpRequest()
xhr.open("GET", "/test/chunked", true)
xhr.onprogress = function () {
  console.log("PROGRESS:", xhr.responseText)
}
xhr.send()